Safety device for electric signaling apparatus.



A. C. FARRAND.

I SAFETY DEVICE FOR ELECTRIC SIGNALING APPARATUS. APPLICATION FILED MAR. H. 1914.

1,146,616. Patented July 13, 1915.

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ALBERT C. FARRANID, OF ATLANTIC CITY, NEW J ERSEY, ASSIGNOR TO H. W. JOHNS- MANVILLE COMPANY, A CORPORATION OF NEW YORK.

SAFETY DEVICE FOR ELECTRIC SIGNALING APPARATUS.

Specification of Letters Patent.

Patented July 13, 1915.

Application filed March 11, 1914. Serial No. 824,033.

To all whom it may concern:

Be it known that l, ALBERT C. FARRAND, a citizen of the United States of America, residing at Atlantic City, county of Atlantic, State of New Jersey, have invented certain new and useful Improvements in Safety Devices for Electric Signaling Apparatus, of which the following is a specification.

My invention relates to signaling apparatus and comprises a safety attachment for such devices.

The particular types of signaling apparatus to which I propose to more particularly apply my invention are fire alarm signaling systems and police signaling systems. In apparatus of this type there are call boxes or signal boxes placed on the street within reach of an adult person usually containing a combination of clock work or magneto, electric apparatus with various electrical circuits connected to an external circuit which runs to a distant station or central oflice. As now and heretofore manufactured, these signal boxes have usually been formed of metal, the clock work and electrical fittings are largely of metal, and while effort is made to insulate the box and the major portion of its contents from the supporting post and the outwardly extending circuit, it frequently happens in cases of kill anyone touching the same. Besides the possibility of the casual passerby placing his hand upon the metal signal box there is also the necessity for a person who desires to send in a signal from'it opening the box and grasping some form of trip member in order to set the signal sending apparatus in operation. Whenever the apparatus is heavily charged with electricity and the ordinary insulation destroyed or insufficient, a person so manipulating the apparatus is liable to be killed or dangerously shocked. Many policemen are killed every year by accidents of this character. It has been proposed to remove some of these difiiculties by providing the trip member with a non-conducting covering at the point where it is grasped by the operator, but this is not alto gether sufficient because said non-conducting covering is liable to be covered by a conducting film of moisture or cracked and the crevices filled with a conducting film of material, and there still remains the possibility of the operators hand reaching beyond the insulated portion and touching a portion of the highly charged metallic structure. I have overcome these difficulties by the simple device of a permanent ground for the exterior surface of the trip member and an arrangement of insulating screens for the rest of the apparatus, all of which will be hereinafter more fully described.

The best form of apparatus at present known to me embodying my invention as applied to a standard form of fire alarm signal system, is illustrated in the accompanying sheet of drawings in which- Figure 1, is afront view of a signal box with the outer door open and parts broken away, Fig. 2, is an enlarged diagrammatic view of the signaling mechanism and hand operated pull-hook or trip lever, and Fig. 3, is a detailed view of a modification.

Throughout the drawings like reference characters indicate like parts.

1, represents the body of the outer box which is of standard form but instead of being made of metal as is usual, is, in accordance with my invention, made of some tough, strong material which is a non-conductor of electricity, such as one of the molded forms of insulating material now on the market. Of course, it might be made of wood, glass or other insulating material. As the door which closes the front opening of said signal box is usually equipped with more or less complicated locking, opening and operating devices, I prefer to retain the present standard form or forms of such signal box outer doors made of metal and such an one is indicated at 2. While this door is of metal it is completely insulated both from the box support and from the internal apparatus and circuits because it is hinged to and in contact with only the body 1, of the outer box which, as before stated, is wholly of insulating material. The usual lock on the dooris indicated a113, and the ordinary form of handle on the outer face of the door is indicated at 4, in dotted lines.

5, 5, are the hinges for door 2.

' 6, is an inner shell located in outer box 1,

containing the clock work and other signal sending apparatus. As the outer box 1, is made of insulating material, this inner shell 6, is preferably made of metal, as at present, but said shell has its entire front left open and this opening is preferably closed by a door 7, of insulating material supported by hinges 8, 8. This door 7, has a flange 9, around its edges, or is otherwise formed, so as to completely cover the front of the inner metal shell (3, and prevent the operator from touching any portion of said metal shell.

10, is the usual keyhole through which the lock on door 7, may be operated and. 11, is a slot or perforation through which projects the pull-hook or trip lever 29., of the signal sending apparatus, all arranged in the usual manner.

While any form of signal sending apparatus and circuits may of course be employed, and the same constitute no part of my invention, 1 have illustrated in a diagrammatic and convenient manner, for the sake of clearness, a possible form of such apparatus in Fig. 2, where 12, indicates a clock work, 13, a contact making drum or wheel operatively connected to the clock work by gearing 27, and 15, 16, represent spring contact lingers adapted to cooperate with the contact drum l8. Circuitwires 1'7, and 18, are connected to contact fingers 15, and 16, respectively, said fingers being normally. insulated one from another by a block :28, of insulating material. These wires 17, and 18, are connected to any suitable exterior circuit extending to the central station or office. As indicated the clock work and gearing connected thereto are normally locked against motion by the detent lever 19, pivoted at 29, to the main frame and having notches 30, 30, with which pins 31, 31, on gearing 27, may engage when the detent lever 19, is in its lowermost position shown in full lines in Fig. 2. 20, is the pull-hook or trip member pivoted to the main frame at 21, and having one end 22, projecting through the slot 11, in door 7. The other end of trip lever 20 engages the outer end of detent lever 19.

in accordance with my invention the outer or projecting end 22, of trip lever 20, is covered more or less with a body of insulating material 23, and a ground wire 25, connected to the exterior of said body of insulation 23, by means of a metal cap 24, or otherwise. As shown in Fig. 1, the ground wire 25, may be conveniently grounded by attaching it to the ground binding screw 26, of the signaling apparatus, though of course any other convenient ground could be substituted.

In Fig. .3, I have shown a slightly modified form of trip lever sometimes used, in which the projecting end 32, is provided with an insulating covering 33, such as a porcelain button or handle. For use on such forms of apparatus, I propose to apply a special form of conducting cap 34, which may be easily slipped over the porcelain 33, said cap being provided with a wire connection 35, which can be conveniently connected to the ground binding screw, as before.

In operation the person desiring to send in fire alarm or other signal opens the outer door 2, and, grasping the exterior or projecting end of the trip lever 20, pulls the same downward. This lifts the detent lever 19, clear of the pins 31, 31, into the position shown in dotted lines and the clock work starts into action, rotating the contact drum or wheel 13, in the direction of the arrow. The projections 36, on said drum or wheel touch one or more of the contact fingers 15, and 16, forcing the; together or bridging the opening between them, thereby completing the signaling circuit 17, and 18, and sending the predetermined number of signaling impulses over said circuit to the centraloflice.

The advantage of my invention arises from the fact that no matter how heavily the clock work and other internal mechanism or inner shell 6, are charged with electricity, as the result of the circuit wires crossing with an electric light or trolley circuit and the breaking down of insulation, no discharge will be produced through the hand and body of the operator. If the charge has been suliicient to break down the insulation 23, or jump over the same, it will pass to the ground harmlessly through the ground wire 25, and as said ground conneotion affords a path of much less resist ance than the body of the operator, no appreciable portion of the current will pass through the operators body. If the hand of the operator reaches over and touches the inner door 7, it is still protected, as this door is of insulating material and acts as a protecting screen to prevent the operator touching the metal shell 6, or any of its contents. No shock can occur from handling the outer door 2, or touching the outer box 1,-as the latter is of insulating material and completely insulates the door 2, from the rest of the apparatus. is thus protected the signal sending device is still maintained in operative condition as no undesirable ground connection to it is established by the safety ground wire 25, under ordinary conditions, and if the charge were sufliciently high in voltage to produce more or less leakage through the insulation 2-3, to the ground, this would be only a high resistance shunt which would still probably leave the operative signal circuits in working condition.

It is very important that fire alarm boxes Nhile the operator shall be maintained in such condition that signals can be sent in from them without danger of serious injury to the operator, even though the connected circuits are crossed with high potential wires and heavily charged thereby in stormy weather, as it is in stormy weather that the wires of light and power circuits are most apt to get crossed and cause fires. My invention, as before explained, secures this result. My invention also protects operators from shocks caused by lightning, which is most important, since in large cities an electric storm may start three or four fires andresult in that number of fire alarm boxes having to be pulled while the electric storm is at its height. If at the moment a box is being pulled, a heavy electrical discharge should seek that circuit as the shortest path from the atmosphere to the earth, the operator might be badly shocked if my safety attachment be not employed.

Another advantage resulting from the use of my invention is that, by reason of the complete protection which it affords the operator, it becomes permissible to use larger fuses in the central office. Consequently, these larger fuses will not blow out as easily in case of crossed wires or lightning discharges and the system will remain longer in service during storms or in the case of crossed wires before the safety fuses blow out.

Of course my safety attachments above described could be applied to other forms of signal sending apparatus in a similar manner, and other arrangements of ground connection substituted, without departing from the principle of my invention so long as the general relation of the parts above described is maintained.

Having described my invention, 1 claim:

1. In an electric signaling device adapted to be manually operated, the combination of a signal sending apparatus, a circuit con nected thereto, a manually operated member for actuating said signal sending apparatus, an insulating covering for that portion of said. member designed to be grasped by the operator, and a ground connection to the exterior of said insulating covering.

52. In an electric signaling device adapted to be manuallv operated, the combination of a signal sending apparatus, a circuit connected thereto, a manually operated member for actuating said signal sending apparatus, a metal cap for that portion of said member adapted to be grasped by the operator, a body of insulating material separating said cap from the main portion of the member, and a ground connection for said cap.

In an electric signaling device the combination of a signal sending apparatus, an electric circuit connected thereto, a box or outside shell formed of insulating material in which the apparatus is contained, and a metal door hinged to said box and forming the face thereof, together with an inner metal shell open at the front in which the signal sending apparatus is mounted and a doorof insulating material hinged to said metal shell and covering the front opening and edges thereof.

4. In an electric signaling device the combination of an electric circuit, an automatically operating circuit making and breaking apparatus included therein, a metal shell for containing said apparatus open at the front, a door of insulating material provided with a perforation, hinged to said shell and covering said front opening, a trip member for the make and break apparatus projecting through said perforation, a body of insulating material on the projecting end of said member, and a ground connection'for the exterior of said body of insulating material.

5. In an electric signaling device the combination of an electric circuit, an automatically operating circuit making and breaking apparatus included therein, a metal shell for containing said apparatus open at the front, a door of insulating material provided with a perforation, hinged to said shell and covering said front opening, a trip member for the make and break apparatus projecting through said perforation, a metal cap for the end of said member projecting through said perforation, a body of insulating material separating said cap from the main portion of the trip member and a ground connection for the cap.

6. A manually operated device for opening and closing an electric circuit comprising in combination a clock work mechanism, a manually operated trip member for said clock Work mechanism, an insulating covering for that portion of the trip member designed to be grasped by the operator, and a ground connection from the exterior of said insulating covering.

7. A manually operated device for opening and closing an electric circuit comprising in combination a clock work mechanism, a manually operated trip member for said clock work mechanism, an insulating covering for that portion of the trip member designed to be grasped by the operator, and a ground connection from the exterior of said insulating covering, together with an insulating screen for said clock work mechanism provided with a perforation through which the insulation covered portion of the trip member projects.

8. As an article of manufacture, a safety attachment for electric signal call boxes designed for manual operation by the movement of a trip lever having a projecting portion of insulating material, which comprises a metal cap adapted to be placed over the projecting insulated portion of said trip lever, and a ground wire connected to said cap.

9. The combination of a manually operated device for opening and closing an electric circuit, an insulating covering for that portion of the device designed to be grasped by the operator, and a ground connection from the exterior of said insulating covering.

10. In an electric signaling device, an insulating inclosing case for the signaling mechanism, comprising a shell of double Wall construction throughout, provided With an opening in each Wall, one of the Walls being formed of insulating material and the other of non-insulating material, and doors closing the openings in the Walls, the outer door being of non-insulating material.

11. In anelectric signaling device, an insulating inclosing case for the signaling mechanism, comprising a shell of double Wall construction throughout, a door of insulating material forming part of the inner Wall and a metal door closing an opening in the outer Wall.

12. The combination of signaling mechanism, a door of metal controlling access to the mechanism, and a body of insulating material providing support for the door and arranged to eifect complete electrical separation oi the door and the signaling mechanism.

ALBERT G. FARRAND.

Witnesses ALLEN B. ENDIooTT, JENNIE F. YOUNG.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. C.

Correction in Letters Patent No. 1,146,616.

It is hereby certified that Letters Patent No. 1,146,616, granted July 13, 1915, upon the application of Albert C. Farrand, of Atlantic City, New Jersey, for an improvement in Safety Devices for Electric Signaling Apparatus, were erroneously issued to H. W. Johns-Manville Company, as owner of the entire interest in said invention, Whereas said Letters Patent should have been issued to the inventor, said Farrand and H. W. J ohns-Mantrille Company, jointly, said corporation being owner of one-half interest only, as shown by the records of assignments in this office; and that the said Letters Patent should be read with this correction therein 7 that the same may conform to the record of the ease in the Patent Office.

Signed and sealed this 27th day of July, A. D., 1915.

R. F. WHITEHEAD,

Acting Commissioner of Patents.

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